Barça has one of the best squads in the world, but it could be argued that Pep Guardiola is still missing a play-making defender to play alongside Piqué and to eventually replace Puyol on the back-line.

Pep Guardiola is considering both Mascherano and Abidal as defenders in the roster for 2011/12, and Andreu Fontás has been promoted from Barcelona B. So if my math is not wrong, that makes five central defenders for two positions.

However, the only "true" play-making back Barça has right now is called Gerard Piqué, and while Fontás is promising and Marc Bartrá is waiting in the wings for an opportunity, adding another technically proficient centre-back wouldn't be half bad.

In this slideshow, we will simply name five options that could fit the bill as good centre-backs for the Blaugrana, with no regard whatsoever to whether or not Pep, Rossell and company actually have them in their sights as potential signings (even though they probably should).

Author's note: This will be my final slideshow (unless someone can point out another potential improvement) in my series of the Role Players Who'd Improve Barça Tactically.

5. Thiago Silva (AC Milan)

Thiago Silva is a fantastic centre-back for sure, and has become the leading man in Milan next to Alessandro Nesta. His ball-playing skills have even let him play as a defensive midfielder, so he fits what Barcelona is looking for.

However, he is accustomed to defending very close to the keeper, while Barcelona defenders usually play way higher up the pitch. Something tells me this will be a huge problem for him if he ever plays for Barcelona.

Case-in-point: he suffered at this year's Copa America with Brazil.

Transfer Value:

His transfer value is around €30 to 40 million, and I doubt Milan will see him leave for a penny less than that.

Overall Improvement Grade: C

He'd cost Barça 30 to 40 million euros, but I doubt he's worth that much. Especially if he's going to be used in a higher defensive line like Barça's. I'm thinking Chygrinskiy or Henrique 2.0 here.